The double-blind and placebo-controlled clinical trials evaluated the acute and chronic effects of Bacopa monnieri on cognitive function in adults with respect to cognitive-enhancing effects, specifically memory, learning and concentration, and supported the traditional Ayurvedic claims attributed to it. The initial chemical investigations described the occurrence of two saponins, designated as bacosides A & B (Chatterjee, N., et al., Indian Journal of Chemistry, 1, 212-215, 1963, Chatteijee, N., et al., Indian Journal of Chemistry, 3, 24-29, 1965). A well designed 12 week study with 46 healthy human volunteers has shown that chronic administration of 300 mg of Bacopa monnieri extract standardized to 55% bacosides, is associated with cognitive-enhancing effects with a significant improvement in verbal learning, memory consolidation, and speed of early information processing in the treatment group compared to placebo (Stough, C., et. al., Psychopharmacology, 156, 481-484, 2001). The acute oral administrations of a single dose of 300 mg of Bacopa monnieri extract standardized to 55% bacosides, however showed no significant changes in cognitive function.
Bacopa's potential to modulate or enhance cognitive function has also been studied in children. A doudle blind placebo-controlled trial carried out on 110 school going children, in the age group of 10-13 using Bacopa monnieri has shown significant enhancement in memory (Abhang R., et. al. Journal of Research in Ayurveda and Sidda, 14, 10-24, 1993). A similar study with 36 children of attention deficit hyperactivity disorder (ADHD) conducted over a 16 week period with a treatment regime for 12 weeks with twice daily dose of 50 mg of Bacopa extract standardized to 20% bacosides showed significant improvements in sentence repetition, logical memory and paired associate learning tasks at 12 weeks and the effects maintained at 16 weeks (Bacopa monniera, monograph, Alternative Medicine Review, 9, 79-85, 2000).
Bacopa's potential as an anti-anxiety remedy has been supported by both animal and, clinical research. In an animal model, its anxiolytic activity was comparable to Lorazepam, a common benzodiazapene anxiolytic drug (Bhattacharya, S. K., et. al., Phytomedicine, 5, 77-82, 1998). A clinical trial of 35 patients with diagnosed anxiety neurosis demonstrated that administration of Brahmi syrup (equivalent to 12 g dry crude extract of Bacopa) resulted in a significant decrease in anxiety symptoms, level of anxiety, level of disability, and mental fatigue, and exhibited considerable increase in immediate memory span (Singh, R. H., et. al., Journal of Research in Ayurveda and Sidda, 1:133-148, 1980).
Other animal and human clinical studies support the beneficial actions of Bacopa monnieri on other indications as well, such as epilepsy, bronchitis, asthma, gastrointestinal disorders and hypothyroidism.
Mechanisms of action: A number of research studies have been initiated to study the mechanism behind Bacopa's therapeutic use for enhancement of cognitive function. The triterpenoid saponins and their bacosides were found to be responsible for Bacopa's ability to enhance nerve impulse transmission. The bacosides facilitate the repair of damaged neurons by enhancing kinase activity, neuronal synthesis, and restoration of synaptic activity, and ultimately nerve impulse transmission (Singh, H. K., et. al., Indian J Pharmacology, 29, S359-S365, 1997). Bacopa extracts modulate the expression of certain enzymes involved in the generation and scavenging of reactive oxygen species in the brain in experimental animals (Chowdhuri, D. K., et. al., Phytotherapy Research, 16, 639-645, 2002). These compounds facilitate the consolidation of the short-term memory and the effect persists even when the intermediate and long-term memories occur. Bacosides appear to have antioxidant activity in the hippocampus, frontal cortex, and striatum of the animals (Bhattacharya S K, et. al., Phytotherapy Research. 14, 174-179, 2000). As the loss of cholinergic neuronal activity in the hippocampus is the primary feature of Alzheimer's disease (Enz, A., et. al., Progress in Brain Research, 98, 431-438, 1993), bacosides may have a therapeutic effect in the treatment of Alzheimer's disease. The bacosides from Boacopa mommieri have the potential to exhibit antistress effects through modulating the activities of Hsp70, P450 and SOD, thereby possibly allowing the brain to be prepared to act under adverse conditions such as stress [Chowdhuri, D. K., et. al., Phytotherapy Research. 16, 639-645, 2002].